Аннотация:For the first time dating of the Khvalynian deposits, opened with boreholes in the Northern Caspian Sea, is executed by 14C AMS method. The obtained dates in the range of 25-56 thousand years are documentary signs of more ancient age of the beginning of the Khvalynian transgression and of significantly bigger duration of the Khvalynian epoch. The obtained data allow to correlate the most part of the Khvalynian epoch of the Caspian Sea with Middle Valday interstadial events of the East European Plain.